1. Field of the Invention
This application relates to an electrical connector and a terminal for use in the electrical connector of the type suitable for use in establishing an interconnector to traces on a circuit panel, especially to a zero or low insertion force electrical connector socket for use in establishing electrical interconnections to a single in-line memory module.
2. Description of the Prior Art
Single in-line memory modules (SIMM) represent a high density, low profile single in-line package for electronic components such as dynamic random access memory integrated circuit components. A plurality of these components can be mounted in line on a circuit panel whose height is little more than the length of the components themselves. The circuit panels can in turn be mounted on a printed circuit board daughtercard which can then be mounted on a printed circuit board mothercard. The spacing between adjacent daughtercards would then need to be only slightly greater than the height of the individual circuit panels or single in-line memory modules.
One approach for mounting single in-line memory modules on a daughterboard would be to employ plug in leads adjacent one edge of the circuit panel. These plug in leads can then be connected to conventional printed circuit board contacts such as miniature spring contacts.
An alternate approach has been to use single in-line memory module sockets to establish a disconnectable interconnection to traces along the edge of the circuit panel used in the single in-line memory module. Terminals for use in such sockets are disclosed in U.S. Pat. No. 4,557,548 and U.S. Pat. No. 4,558,912. Additional details of an insulative housing which is suitable for use with those terminals is disclosed in U.S. Pat. No. 4,781,612. The socket disclosed in these patents is intended for use with in-line memory modules having a center line spacing for pads or traces at the edge of the circuit panel of 0.100 inch. Since the terminals employed in that socket are stamped and formed, the width of the terminals generally precludes establishing an interconnection on closer center line spacings.
Instead of using stamped and formed terminals, other single in-line memory module sockets employ edge stamped terminals. For example, U.S. Pat. No. 4,737,120 discloses an electrical connector of the type suitable for use in a single in-line memory module in which a zero or low insertion force interconnection is established between the terminals and the pads on the circuit panel. The circuit panel is inserted at a angle and then cammed into position. The insulative housing on the connector provides a stop to hold the circuit panel in position. Other low insertion force connectors are disclosed in U.S. Pat. No. 4,136,917; U.S. Pat. No. 4,575,172; U.S. Pat. No. 4,826,446 and in U.S. Pat. No. 4,832,617. The contact terminals in each of these patents is edge stamped Sockets using terminals of this type are suitable for use on center line spacings on the order of 0.050 inches.
Not all commercially available single in-line memory modules are manufactured in compliance with generally accepted standards for such modules, such as appropriate JEDEC standards. Nonstandard single in-line memory module circuit panels are manufactured with the pad portions of the traces adjacent the edge of the circuit panel being shorter than required by industry acknowledged standards. Deviations in JEDEC standards have also occurred because some module manufacturers have been unable to maintain a tolerance of .+-.0.003 inches on the module thickness as required by JEDEC. Tolerances of .+-.0.008 inches are more realistic; but such tolerances complicate the design of the terminal because a larger deflection range is necessary.
U.S. Patent Application 07/360,644 filed June 2, 1989, discloses a full force socket suitable for use with nonstandard circuit panels or single inline memory modules. The instant invention discloses a zero or low insertion force circuit panel socket suitable for use with nonstandard single inline memory modules.